Bi atom sharing Co-Bi2O2CO3/BiOI S-scheme induced singlet oxygen-dominated photocatalytic oxidation system

Endocrine disrupting chemicals (EDCs) interfere with the normal secretion, transport and metabolism of human hormones, thus affecting neurological, reproductive and immune functions. Photocatalysis is regarded as a facile organic degradation technique. The construction of heterojunctions can modulate the reactive oxygen species and enhance the photocatalytic performance of semiconductors. However, poor contact interfaces still severely limit carrier separation and transfer. Herein we have doped Co to modulate the band structure of Bi₂O₂CO₃ while facilitating the in situ growth of BiOI on its surface via shared Bi atoms. This approach led to the development of a 2D/2D Co-Bi₂O₂CO₃/BiOI (Co-BOC/BiOI) S-scheme heterojunction characterized by atomically close contact interfaces. Furthermore, the photo-electrochemical characterization results indicate that the light adsorption capacity, carrier separation and transport efficiency of the optimized Co-BOC/BiOI-3 are greatly improved. This system demonstrates almost 100% removal rate for three typical EDCs within 60 min. The degradation kinetic constants show an improvement by an order of magnitude compared to single BiOI and Bi₂O₂CO₃. More importantly, O₂^•﹣, which is produced from O₂ reduction on high negative conduction band, can be subsequently oxidized into ¹O₂ by photogenerated hole. Electron paramagnetic resonance and quenching experiments indicate that the organics degradation process is dominated by ¹O₂. This work offers new insights into the construction of high-quality S-scheme heterojunction interfaces for modulation of reactive oxygen species.